package com.vadmin.vadminjava.common;
 
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class MD5FileUtil {
 
  protected static char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e',
       'f' };
  protected static MessageDigest messagedigest = null;
 
  static {
     try {
       messagedigest = MessageDigest.getInstance("MD5");
     } catch (NoSuchAlgorithmException e) {
     }
  }
 
  public static String getFileMD5String(File file) throws IOException {
     FileInputStream in = new FileInputStream(file);
     FileChannel ch = in.getChannel();
     MappedByteBuffer byteBuffer = ch.map(FileChannel.MapMode.READ_ONLY, 0, file.length());
     messagedigest.update(byteBuffer);
     return bufferToHex(messagedigest.digest());
  }
 
  public static String getMD5String(String s) {
     return getMD5String(s.getBytes());
  }
 
  public static String getMD5String(byte[] bytes) {
     messagedigest.update(bytes);
     return bufferToHex(messagedigest.digest());
  }
 
  private static String bufferToHex(byte bytes[]) {
     return bufferToHex(bytes, 0, bytes.length);
  }
 
  private static String bufferToHex(byte bytes[], int m, int n) {
     StringBuffer stringbuffer = new StringBuffer(2 * n);
     int k = m + n;
     for (int l = m; l < k; l++) {
       appendHexPair(bytes[l], stringbuffer);
     }
     return stringbuffer.toString();
  }
 
  private static void appendHexPair(byte bt, StringBuffer stringbuffer) {
     char c0 = hexDigits[(bt & 0xf0) >> 4];
     char c1 = hexDigits[bt & 0xf];
     stringbuffer.append(c0);
     stringbuffer.append(c1);
  }
 
  public static boolean checkPassword(String password, String md5PwdStr) {
     String s = getMD5String(password);
     return s.equals(md5PwdStr);
  }
 
}
